Fixative device for decorative finial

ABSTRACT

A fixative device for a decorative finial capable of being press fit onto a picket or post includes a pair of contact tabs arranged to bridge across a bend or corner formed by the inner surface of the free end of a tubular picket or post. A fit may be provided by a channel and protrusion or o-ring. 
     A plurality of contact tabs, each having two contact surfaces may accommodate manufacturing defects and variations in the wall thickness of tubular, extruded posts.

FIELD OF THE INVENTION

The field relates to decorative finials.

BACKGROUND

Decorative finials are known that are press fit onto tubular posts. However, irregularities in the wall thickness of commercially available tubular posts makes press fittings unreliable resulting in loose or displaced finials. An improved, yet inexpensive and easy to fix finial that overcomes this disadvantage is a long standing and unresolved need.

SUMMARY OF THE INVENTION

A device for fixing a decorative finial on a tubular post has a tubular portion shaped to fit on and/or in the top of a tubular post. A tubular post, having various cross sections shaped as square, rectangular, triangular, round and other cross sectional shapes, are well known in the art. The tubular portion extends downwardly from an end wall, the end wall at least partially closing a first end of the tubular portion, a second end of the tubular portion being open, whereby the tubular end of the tubular post is insertable over or within a tubular post. The tubular portion is defined, for example, by four walls and four corners, two of the four walls form a first corner and the other two walls form another of the four corners opposite of the first of the four corners.

A corner tab is proximally disposed at the first corner, having two contact surface joined by a member extending outwardly from a portion of the end wall. A gap is defined between each of the two contact surfaces and the tubular portion of the device. The corner tab extends diagonally across the corner, and a second corner tab is proximally disposed to a second corner opposite of the first corner tab and the first corner. The contact surfaces are proximally located to walls, defining a gap between each of the contact surfaces and the walls defining a corner of a substantially polygonal tubular extension from the bottom of the finial, for example.

The wall of the tubular portion of the finial and contact surfaces on opposite sides of the contact tabs define a gap having a width. The gap width may vary along the length of the contact surfaces extending from the bottom of the finial or may be constant. For example, gap width is chosen to allow the contact surfaces of the contact tab to make contact with the inner walls of a tubular post.

For example, two contact tabs disposed diagonally across opposite corners of a tubular post with a square or rectangular cross section have four contact surfaces, which are capable of contacting each of the four sides of the inner tubular wall of the post, providing a press fit fitting. In one alternative example, a tubular wall is omitted from the finial, and contact tabs are used to press fit the finial in the open tubular end of the post. Regardless, the contact tabs may be substantially rigid or may be designed to be at least somewhat flexible. For example, the thickness of the contact tab may be selected such that the elastic modulus and stiffness of the material accommodates some variation in the thickness of the tubular wall of the post, when a decorative finial is fitted on the end of the tubular post. The contact surfaces may be narrower at one portion along the contact surface, such as at the base of the contact tab or at a point between the base and the free end of the contact tab, allowing for an elastic pinching of the wall of the tubular post between the outer surface of the tubular portion of the decorative finial and the contact surfaces.

In another example, contact tabs may be disposed diagonally at each corner of a triangular, square or rectangular cross sectional shape. One advantage of diagonally positioned contact tabs is that redundancy is provided, when more than two tabs are provided. Another advantage is that the width of one or more of the contact tabs or the position of one or more of the contact tabs may be varied compared to one or more of the other contact tabs, such that two or more different wall thicknesses of tubular posts may be accommodated with a single decorative finial.

For example, a first pair of tabs, each having a base, may be disposed diagonally across opposite corners of a the tubular portion of a decorative finial at a first base-to-base distance, and a second pair of tabs disposed rotationally ninety degrees from the first pair of tabs may be disposed at a second base-to-base distance less than the first base-to-base distance. The gap defined between contact surfaces of the first pair of tabs and a tubular portion of the decorative finial is narrower than the gap defined between the contact surfaces of the second pair of tabs and the tubular portion. The first pair of tabs, having a narrower gap width, may be used to secure the decorative finial to posts having comparatively thin walls, while the second pair of tabs, having a wider gap width may be used for posts having thicker walls.

For example, the first pair of tabs, having a narrower gap width, may be designed to break off when a post with a thicker wall is encountered, or a user may use a screw driver or other prying device to break them off, leaving only the tabs with the wider gap width.

One advantage of a fixative using corner tabs is that each corner tab provides two contact surfaces, which may contact two different walls of a tubular post. Another advantage is that a single pair of corner tabs in opposite corners of a post having a square or rectangular cross section is sufficient to secure the decorative finial on the post. Yet another advantage is that a decorative finial may be fixed in place by corner tabs without the need for any tubular portion extending outwardly from the bottom of the decorative finial. A plurality of corner tabs may be pinched within the cavity formed by an open tubular end of a post, fixing the decorative finial on the post by a press fit. Yet another advantage is that the corner tabs may be made of a substantially rigid material, such as metal or a stiff polymer, yet may also provide some elasticity based on a material's elastic modulus and the thickness and design of the corner tabs. Thus, the decorative finial may be positively clamped in place by the elastic and compression forces acting on the corner tabs.

Still another advantage is that additional tabs may be added to improve retention and to provide damage tolerance, if one or more tabs is broken or defective. Yet another advantage is that tubular posts having substantially different wall thicknesses may be accommodated using a single decorative finial with tabs having a plurality of gap widths. Still yet another advantage is accommodating tubular posts having substantial irregularities in wall thickness using the fixative device. Yet another advantage is accommodating tubular posts with substantial irregularities in the wall thickness at corners, because the contact surfaces of the tabs avoid contact of the diagonally disposed tabs with the walls at the corners.

BRIEF DESCRIPTION OF THE FIGURES

The drawings describe some examples of the features of a fixative device for a decorative finial.

FIG. 1 illustrates an example of a decorative finial having two contact tabs.

FIG. 2 illustrates a bottom perspective view of the fixative device in FIG. 1.

FIG. 3 illustrates a finial having four corner tabs with hidden lines representing location of corner tabs in a side plan view.

FIG. 4 illustrates another bottom perspective view of the finial of FIG. 1.

FIG. 5 illustrates another example in a bottom perspective view of a finial having four corner tabs.

FIG. 6 illustrates another example in a bottom plan view of a finial having four corner tabs and a connecting support structure.

FIG. 7 illustrates another example in a bottom plan view of a finial having four corner tabs.

FIG. 8A illustrates a side plan view of a decorative finial's narrow side.

FIG. 8B shows a side plan view of the broadside of the finial of FIG. 4.

FIG. 8C depicts a perspective view of the underside of the finial in FIGS. 8A and 8B.

FIG. 9 illustrates a perspective view of a portion of a cross-section of a wall.

FIG. 10 illustrates a bottom perspective view of alternative connecting support structures in another example of a fixative device.

DETAILED DESCRIPTION

Numbered labels identify exemplary features in the drawings. The same numbers are used in multiple drawings to show the same or similar features in the drawings.

Now referring to FIG. 1, an example of a decorative finial has a bottom portion with a flange 12. A tubular wall 15 extends outwardly from the bottom of the decorative finial. Tabs 32 extend outwardly from the bottom of the decorative finial and are disposed diagonally across one of the corners 17 of the tubular wall 15. FIG. 2 illustrates a bottom plan view of the arrangement of a plurality of corner tabs 32 integrally formed in a process of molding the decorative finial, such as in a die injection process of a metal or polymer material. For example, aluminum die injection may be used to integrally form the flange 12, tubular wall 15, and four corner tabs 32 in a single die injection process.

In the example of FIG. 2, each of the tabs 32 has two contact surfaces 34, 36, which extend along opposite sides of the tab 32. The contact surfaces 34, 36 are designed to press fit onto an open, tubular end of a post (not shown), which is well known in the art of extruded posts, for example. The base 33 of each corner tab 32 may be thicker than the free end 35, if additional stiffness and damage tolerance of a tab 32 is desirable. Each of the two contact surfaces 34, 36 of the diagonal corner tabs 32 are capable of making contact with an inner surface of the free end of a post for securing the decorative finial on the post.

In the example of FIG. 3, the flange 12 extends radially outward from the tubular wall 15 providing additional structural support to the wall 15. The tabs extend outwardly from a bottom 11 of the decorative finial. The decorative finial 1 extends up from a necked region 3. Two of the four corner tabs 32 are shown by omitting one side wall of the tubular wall 15. Likewise, all four side walls may be omitted, if the additional strength provided by the tubular wall 15 is not desired.

In the example of FIG. 4, two corner tabs 32 are disposed diagonally across two opposite corners 17. Contact surfaces 34, 36 of each of the two tabs 32 are capable of making contact with adjacent wall portions on either side of a free end of a post (not shown), which is shaped and sized to fit inside the tubular wall 15. Collectively, four points of contact are established by the contact surfaces 34, 36 of both tabs 32, which is capable of press fitting the decorative finial on the free end of the post. Thus fewer tabs and less material is required for integrally forming or casting a decorative finial than for conventional finials with tabs running along side walls. Alternatively, additional tabs 17, such as shown in FIGS. 5, 6, 7, and 10, may be used to provide damage tolerance and fewer rejections of decorative finials based on casting or forming defects or variations in post wall thicknesses, for example.

In the example of FIG. 5, the plurality of tabs 52 are shaped differently than the tabs 32 of FIGS. 1-4. The tabs 52 still have two contact surfaces 54, 56, but the contact surfaces 54, 56 are less pronounced. The tabs 52 have a narrower width A at the base 53 than the tabs 32 of FIGS. 1-4 and are narrower at the top 53 of the tabs 52, also. Nevertheless, each of the tabs 52 has two contact surfaces 54, 56 that define a gap of width B between the widest portion of the contact surfaces 54, 56 and the tubular wall 15. If the wall thickness of the free end of a post has a given thickness slightly greater than or equal to B, then the contact surfaces 54, 56 make contact with the inner surface of open, tubular end of the post, press fitting the decorative finial on the post, for example. The contact surfaces 54, 56 may be made of an elastic material, which is capable of elastically deforming when the finial is pressed onto the end of a post having a wall thickness greater than B. In one example, the entire corner tab 32, 52 may have sufficient elasticity to provide a positive locking (or outwardly pinching) force against the inner surface of the end of the post. Both metals and polymers may have sufficient elasticity to fix a finial on the end of the post. Alternatively, an elastomeric material, such as a natural or synthetic rubber material, an adhesive, or a tacky coating may be applied or formed on the contact surfaces 34, 36, 54, 56 to elastically fix the finial in place on the post.

Yet another example of corner tabs 62, having contact surfaces 64, 66 are shown in FIG. 6. The corner tags 64, 66 have an additional extension 67 stiffening the tabs 62 from deformation and mechanical failure. The extension 67 are continuously connected and radiate from a central “x.”

Now referring to FIG. 7, a finial similar to FIGS. 1-3 is shown, except that 4 corner tabs are disposed in a first pair and a second pair, which accommodates posts having ends with substantially different wall thicknesses. While the maximum width at the base A may be the same or different for each of the tabs 72, the gap distance B between the inner surface of the tubular wall 15 and the contact surface B, B′ may also be the same or different for each tab 72, or more preferably for pairs 71, 77 of diagonally opposite tabs 72. A first pair 71 of diagonally opposite tabs 72 may be spaced further apart than a second pair 77 of diagonally opposite tabs 72. If the tubular wall 15 is square, as in this example, then the gap width B between a contact surface 74 and the inner surface of the tubular wall 15 of the first pair 71 of diagonally opposite tabs 72 is less than the gap width B′ of the second pair 77 of diagonally opposite tabs 72. In one example, an installer may use a screw driver or other prying device to quickly remove the first pair 71 of tabs 72, if the gap width B is too narrow to properly fit a post with a thick end wall, allowing the second pair 77 of tabs 72 to secure a finial on a post. In another example, the first pair 71 include tabs that self detach or deform, allowing a finial to be pressed onto a post without requiring the installer to manually remove the first pair 71 of tabs 72, if the end wall of the post is too thick for the gap width B. For example, the material for the first tabs 72 may be selected from a material with a yield stress or fracture stress less than the stress imposed on the tabs 72 by pressing the finial on the end of a post with a comparatively thick wall. Alternatively, the first pair 71 of tabs 72 may be scored or notched to provide for a stress concentration at the notch, which can be selected to cause fracture or bending of a tab 72 when the post thickness exceeds the gap thickness B.

FIGS. 8A-8C illustrate another example, which is similar to previous examples except that the tubular wall 85 has a rectangular cross section when viewed from a top planar view or bottom planar view. The side planar view of FIG. 8A shows the view of a narrow side (with transparent sidewall for view of corner tabs 82). FIG. 8B shows the same finial with a side view of the wider side (broad side), showing that the tabs 82 are spaced apart different distances in the side view of 8A and the side view of 8B. The bottom perspective view shows the four tabs 82 diagonally disposed at each of the four corners of the rectangular tubular wall 85 of the finial, such that a gap width is formed between each of the contact surfaces 84, 86 and the inner surface of the tubular wall 85. In one example, the base width A of each of the first pair 71 of the tabs 72 is greater than the base width of each second pair 77 of tabs 72, such that the gap width B is less than B′. In another example, the base width A of each of the tabs 72 is substantially the same, within manufacturing tolerances; however, the distance between the first pair 71 and the second pair 77 of tabs 72 is greater, such that the gap width B is less than B′. Alternatively, both the distance and the base width A may be selected to provide a first designed gap width B and a second desired gap width B′.

Other cross sectional geometries, such as triangular (3-sided) tubes (not shown) and tubes having 5 or more sides (not shown) may be fixed using corner tabs according to the examples already disclosed. A gap width may be established between an inner wall of a tubular member, of any cross section, and contact surfaces of a plurality of corner tabs. The gap width may vary from smaller at the base to larger at the free end of the tab, for example. Alternatively, a portion of the contact surface may extend outwardly creating a restriction between an intermediate portion of the contact surface and the inner surface of the tubular wall. In another alternative, the inner surface of the tubular wall 15, 85 may have an indent or channel 95 formed that may accommodate a protrusion (not shown) or an original (not shown), which may have a shape capable of being accommodated by as the channel 95. The protrusion may be applied or integrally formed on the exterior portion of the end of the post, such that a snap fit results, when the protrusion engages the indent or channel 95. 

1. A device for fixing a bottom end of a decorative finial on a post having a tubular, open end, the device comprising: a first corner tab extending from the bottom end of the decorative finial; and a second corner tab extending from the bottom end of the decorative finial, disposed on an opposite side of the decorative finial from the first corner tab; wherein the first corner tab and the second corner tab each comprise a member having a first contact surface on a first side of the member and a second contact surface on a second side of the member opposite of the first contact surface, such that each of the first contact surface and the second contact surface of each of the first corner tab and the second corner tab are capable of engaging an inner surface of the open end of the post, the first contact surface of each of the first corner tab and the second corner tab making contact on one side of a corner in the open end of the post and the second contact surface making contact on the other side of the corner opposite of the first contact surface, securing the device on the post, when the device is fitted on the end of the post.
 2. The device of claim 1, further comprising a tubular portion extending outwardly from the bottom end of the decorative finial and being disposed such that the tubular portion defines a gap between the tubular portion and each of the first contact surface and the second contact surface of each of the first corner tab and the second corner tab.
 3. The device of claim 2, wherein the tubular portion is shaped as a square or a rectangle, having four sides and four corners, for fitting over the open end of the post, a first corner of the four corners is opposite of a second corner of the first corners, the first corner tab being disposed diagonally across the first corner, and the second corner tab being disposed diagonally across the second corner.
 4. The device of claim 3, further comprising at least one additional corner tab, extending from the bottom of the decorative finial, and each of the at least one additional corner tabs being disposed diagonally across one additional corner of the four corners other than the first corner and the second corner.
 5. The device of claim 4, wherein the at least one additional corner tab comprises a third corner tab and a fourth corner tab, opposite of the third corner tab and disposed diagonally across a fourth corner of the tubular portion.
 6. The device of claim 5, wherein the gap between the tubular portion of the device and each of the first contact surface and the second contact surface of each of the first corner tab and the second corner tab has a minimum gap width substantially less than a minimum gap width of the a gap between the tubular portion of the device and each of the first contact surface and second contact surface of each of the third corner tab and the fourth corner tab.
 7. The device of claim 6, wherein the distance between the first contact surface of the first corner tab and the first contact surface of the second corner tab is greater than the distance between the first contact surface of the third corner tab and the first contact surface of the fourth corner tab.
 8. The device of claim 6, wherein the member of each of the first corner tab and the second corner tab has a first minimum width defined at the narrowest point between the first contact surface and the second contact surface of each of the first corner tab and the second corner tab, and the first minimum width is greater than a second minimum width defined at the narrowest point between the first contact surface and the second contact surface of each of the third corner tab and the fourth corner tab. 